Epidemiology of Grapevine leafroll associated virus-3 and regional management

Transcription

1 Epidemiology of Grapevine leafroll associated virus-3 and regional management

2 Acknowledgements Funding sources: American Vineyard Foundation (AVF) California Grape Rootstock Improvement Commission California Grape Rootstock Research Foundation The Fruit Tree, Nut Tree and Grapevine Improvement Advisory Board (IAB) Collaboration: Foundation Plant Services Neil McRoberts QBE Lab Deborah Golino Vicki Klaassen Maher Al Rwahnih Monica Cooper Rhonda Smith Andrew Walker Sue Sim Grower Community Students

3 Today s Roadmap Virus Introduction GLRaV-3 Epidemiology Regional Management

4 Virus Introduction Grapes are asexually propagated..and so are viruses Rootstock and scion Graft transmissible Top-working is risky Many viruses likely entered the US in infected material Over 70 virus and virus like diseases in grapes

5 Leafroll Healthy Infected Limited sugar, 1-4 Brix Color reduced Yield reduced Irregular ripening, delayed TA increased Graft incompatibility Disease severity depends on variety, clone, rootstock, site, year, leafroll type Photo courtesy of FPS

6 Money Money

7 How much? $226,000 per hectare

8 California Grapevine Registration and Certification (CGR&C) program Provides virus tested true to type planting material $50 MILLION/YEAR BENEFIT Photo courtesy of FPS Certified Material

9 How does that work?

10 Grape Virus Elimination Therapy Collect apical shoot tips Excise meristem dome and 1-2 pairs of leaf primordia Treated selections selections selections selections selections

11 Process Description: Grapevine Importation through Foundation Plant Services, UC Davis (Simplified) Document # FPS UC Regents S. Sim Revised March 6, 2012 YEAR 0 YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR 9 Customer submits Service Request Form to FPS and identifies supplier. Supplier collects wood ships it to APHIS, Beltsville, MD APHIS inspects forwards shipment to FPS Field Index Graft onto indicators: Cabernet franc Kober 5BB LN-33 St. George Read leaf symptoms on St. George, Spring Read trunk symptoms on St. George, LN- 33, and 5BB, Summer Read leaf symptoms on Cabernet franc Fall Yolo county inspects shipment when opened. FPS assigns Accession number and Plant ID numbers. Mist Propagated Plants Available Provisional status Mist Propagated Plants Available Provisional status Qualifies for California Registered Foundation Stock Separate Canes into 2 Bundles 96 buds (ideal) for field index 8 canes for propagation Canes for propagation Index buds Fungicide, Pesticide, Hot water dip Propagate Make 8 plants Move 4 plants to screenhouse for growing season Growing 4 plants in large pots Evaluate Tests Test Results negative APHIS and CDFA authorize release Plant in Foundation Vineyard Grow and Train Trunk and Cordons Professional Identification DNA and/or Visual California Registered Material Available Keep 4 plants in greenhouse for testing and tissue culture in winter LAB TEST Herbaceous host testing, ELISA for nepoviruses, fleck, Spring LAB TEST PCR and ELISA Fall Tests positive Visual Inspection Fall LAB TEST ELISA for nepoviruses, fleck, Repeated, Spring Visual Inspection Fall LAB TEST ELISA for nepoviruses, fleck, Repeated, Spring, Note: The green arrow represents a best case scenario in which a grape introduction tests negative for all viruses and establishes rapidly in the vineyard. The purple arrows represent best case scenarios in which tissue culture treatment successfully eliminates virus and the vine establishes rapidly in the vineyard. Presumptive Tissue Culture for VIP Selections Tissue Culture for virus elimination Growing From 4 inch pot to 2 gallon pot; harvest woody buds for index Tests Tests positive Field Index To determine treatment outcome Growing LAB TEST To determine treatment outcome. PCR and ELISA Growing From 4 inch pot to 2 gallon pot; harvest woody buds for index Read Spring Field Index To determine treatment outcome positive Read Summer Growing Growing LAB TEST To determine treatment outcome. PCR and ELISA Read Fall Evaluate Test Results Read Spring Tests positive APHIS Tests and neg. CDFA authorize release Read Summer Growing Mist Propagated Plants Available Provisional status Plant in Foundation Vineyard Visual Inspection Fall Read Fall Evaluate Test Results Mist Propagated Plants Available Provisional status Grow and Train Trunk/ Cordons LAB TEST ELISA Repeated, Spring Tests positive APHIS Tests and neg. CDFA authorize release Verify ID Visual Inspection Fall Mist Propagated Plants Available Provisional status Plant in Foundation Vineyard Visual Inspection LAB TEST ELISA Repeated, Spring, Mist Propagated Plants Available Provisional status Grow and Train Trunk/ Cordons LAB TEST ELISA Qualifies for CA Reg. Foundation Stock California Registered Material Available Verify ID Visual Inspection Qualifies for CA Reg. Foundation Stock LAB TEST ELISA California Registered Material Available Fall Repeated, Fall Repeated, Spring Spring,

12 Supply Chain Production Vineyards Registered Increase Blocks Foundation FPS Nurseries Growers

13 Backyard safaris.? Just say no!

14 Leafroll spreads Rosciglione, B., and Gugerli, P Transmission of grapevine leafroll disease and an associated Closterovirus to healthy grapevine by the mealybug Planococcus ficus Signoret. Pages in: Proc. ICVG, 9th. 2008

15 How does it spread?

16 Temporal Analyses

17 Spatial Analyses 1. Overlay vineyard block maps with sampling grid, n=4 2. Count vine disease status in each quadrat, proportions 3. Examine the statistical properties of the incidence at two scales Laurence V. Madden, Gareth Hughes, and Frank van den Bosch. The Study of Plant Disease Epidemics APS Press, St. Paul, MN.

18 Spatial Analyses Disease incidence: Proportion of infected plants in the block DI=96/400=24% Quadrat Incidence: Proportion of infected quadrats in the block QI=58/100=58% Laurence V. Madden, Gareth Hughes, and Frank van den Bosch. The Study of Plant Disease Epidemics APS Press, St. Paul, MN.

19 Spatial Analyses Nearest neighbors are more likely to become infected than vines farther away

20 Spatial Analyses Spatially very similar

21 % INCIDENCE Leafroll Epidemiology 70% %-5% %-50%+ Great source of inoculum 1 TIME Random Introduction of Infection Events Aggregation Stage, with some added random infections leading to aggregation

22 Plant certified material Reduce inoculum/rogue infected vines Control vectors Management

23 Napa Valley

24 Napa Valley, CA, leafroll Vector: Grape mealybug Replant infected blocks, rogue new infections, fallow <1% leafroll